Electromagnet



Oct. 14, 1941. J. EATON ELECTROMAGNET Filed Aug. 28, 1939 //V5ULAT/0/V Inventor- John Eaton, by 1/ M 6 His Attovneg- Patented Oct. 14, 1941 I 2,259,127 ELECTROMAGNET John Eaton, Schenectady, N. Y., assignor to General Electric Company,

Yorka corporation of New Application August 28, 1939, Serial No. 292,205

2 Claims.

My invention relates to electromagnets and has for its object a simple, rugged and inexpensive magnet core structure.

To assure the release of the armature member and avoid the possibility of its being held in place by residual magnetism when the coil is deenergized, electromagnets are conventionally vention, reference should be' had to the accompanying drawing, Fig. 1 of which is a side ele-,

vation view of an electromagnetic relay embodying my invention; Fig. 2 is an end elevation view of Fig. 1; Fig. 3 is an enlarged fragmentary exploded view of the magnet core structure; while Fig. 4 is a perspective view of a modified form of my invention.

Referring to the drawing in one form of my invention I provide three core members or groups of laminations I0, II and I2 secured together in overlapping side by side relation, the group being arranged between the other twogroups and separated therefrom by relatively thick layers or sheets of a suitable electrically insulating .material I3 and I 4, such as mica or a fiber, on

each side of the group I0 and forming an air gap between this group and each of the two other groups. The central group I0 is formed from a plurality of laminations made of magnet core iron of U-shape. The laminations of the other outer groups II and I2 are.L-shaped and clamped against the lower leg Illa and the middle portion lb of the central group I0. Preferably as shown, the upright legs or arms Ho and Ho of the two outer groups are of the same length as the middle portion or arm lb of the group ID to which the legs Ha and |2a are secured. The other lower legs of the groups H and I 2 are longer than the leg Illa of the group I0 secured between them. As shown in Fig. 3, the horizontal leg Nb of the group II has a projection extending toward the left-hand beyond the end of the leg Illa, i. e. the inner end of the central core member. Likewise, the horizontal leg (not shown) of the group I2 projects beyond the central leg Ina in the same manner as the leg Hb. It will be understood that the laminations in group III are identical in size with each other as are also the laminations in the other two groups.

The projecting end l5 forms a continuation of the magnet core beyond the end of the central group the same being true of the projecting end (not shown) of the group I2. As shown in Figs. 1 and 2, the exciting coil l5 for the magnet is mounted on the upper horizontal leg Inc of the central group and induces a magnetic flux, when it is energized, in the central group. It will be noted that the ends I5 form one pole of the magnet and the end of the leg Illc, i. e. the projecting end of the central core member .forms another pole of the magnet. This flux,

however, because of the short lower leg Illa of this group and the air gap between the end of this leg and the armature l8 must'jump across the air gaps formed by the layers of insulation 13 and I4 tothe two outside groups, then pass to the outer ends l5 to which the armature I8 is secured and thence to the armature.

By means of this construction, it will be observed that an air gap of relatively large area in a direction at right angles to the flow of flux is provided by each of the layers of insulation. This provides for efficiency in the flux conducting characteristics of the core. Moreover, this arrangement provides for rigidity of assembly by means of the rivets I9, 20 and 2| passing through the groups;

Preferably as shown the projecting ends ['5 are each provided with a suitable notch 22 forming a pivot bearing in which a lateral projection 23 on each side of the armature I8 is pivoted. As shown, the armature l8 carries an electric contact 24 arranged to engage, when the armature is picked'up, with a stationary contact.25. A stop 26 limits the movement of the armature in its unattracted position, shown in the drawing, the armature, being biased to this position by a suitable tension spring 21. A suitable shading coil 28 is provided on the upper end portion of the central group.

It will be understood, of course, that the core in certain instances may not be laminated and, as shown, relatively thin laminations are provided in the central group only, the two outer groups being each formed of two relatively thick laminations while the armature I8 is not laminated. Also, the combined cross sectional area of the magnetic flux conducting material in the two outer groups of laminations H and I2 equals a major portion of the cross sectional area of magnetic flux conducting material in the central group of laminations [0. It will also be understoodthat these parts are all made of magnet core iron. For example, each group may be made of a single unlaminated piece.

Thus the three groups of laminations are joined together by their first overlapping arms while their second arms extend from the overlapping arms in parallel relation with each other to form'with the overlapping arms a U- shaped magnet core, one leg of which is the central leg Ito and the other leg is constituted by the two horizontal legs of the two outer groups H and I2.

Also it will be noted that if the lower leg Illa of the central section were omitted, the magnet core would be magnetically complete by reason of the side by side engagement of the leg remaining formed by the present central section lllb andthe two outer groups. A construction of that type is shown in Fig. 4. This construction may be satisfactory in certain applications.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications'may be made and I, therefore, contemplate by the appended claims to Q cover any such modifications as fall within the true spirit and scope'of my invention..

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electromagnet comprising three L- core member and the second arms of the two outer core members extending from opposite of said-legs upon energization of said coil, and

, position, said air gaps shaped core members of magnetic fiux conducting material having first arms secured together in side by side overlapping relation with each other, and with the second arm of the middle magnet core, one leg being constituted by the second arm of said middle core member and the other leg being constituted by the second arms of said outer core members, the combined cross sectional areas of ,magnetic flux conducting material in saidtwo outer core members being equal to at least a major portion of the cross sectional area of magnetic flux conducting material in said middle core member, and said two legs forming each a sole magnetic flux conducting path through said magnet core at its free end and throughout a substantial portion of its means biasing said armature to an unattracted being of sumcient length to prevent holding of said armature in its attracted position by residual magnetism in said magnet core.

2. An electromagnet comprising three L- shaped core members of magnetic flux conducting material. having first arms secured together in side by side' overlapping relation with each other, and with the second arm of the middle core member and the second arms of the two outer core members extending from opposite ends of said overlapping arms thereby to form two substantially parallel legs of a U-shaped magnet core, one leg being constituted by the second arm of said middle core member and the other leg being constituted by the second arms of said outer core members, the combined cross sectional areas of magnetic flux conducting material in said two outer core members being equal to at least a major portion of the cross sectional area of magnetic flux conducting material in said middle core member, and said two parallel legs forming each a sole magnetic flux conducting path through said magnet core at its free end and throughout substantially its entire length, relatively thick sheets of electrically in sulating material structurally separate from holding of said armature in its attracted posisaid magnet core.

tion by residual magnetism in JOHN EATON.

thick sheets of electrically in I 

